CN102410552B - Large-scale centralized preparation system for pulverized coal and distribution method - Google Patents

Abstract

The invention discloses a large-scale pulverized coal centralized preparation system and distribution method. The system dries raw coal in a drying system by utilizing the heat energy of a power generation enterprise in a raw coal production area, and the dried coal is input into a grinding system to be processed into qualified pulverized coal, and then Use the conveying equipment to transport qualified pulverized coal to coal power enterprises and other pulverized coal users for users to use. The entire pulverized coal processing and transportation process is in an inert environment to ensure the safe operation of the entire system. The invention is mainly applied to large-scale centralized pulverizing plants in mining areas that provide coal powder to coal power enterprises and other coal powder users by transporting qualified coal powder.

Description

A large-scale pulverized coal centralized preparation system and distribution method

Technical field:

The invention belongs to the field of coal power, and relates to a safe and efficient large-scale pulverized coal centralized preparation system and distribution method, in particular to an efficient and clean large-scale pulverized coal preparation system and distribution method.

Background technique:

The power industry occupies an important position in my country's national economy and is an important guarantee for the stable operation and sustainable development of my country's social economy. As an important energy industry in my country, power industry enterprises are duty-bound to save energy, reduce emissions, and achieve low-carbon development. my country's energy structure of "rich in coal, poor in oil, and low in gas" determines that coal power will remain the main force of my country's power production for a considerable period of time in the future. By the end of 2010, the national power generation equipment capacity was 962.19 million kilowatts, of which thermal power installed capacity was 706.63 million kilowatts, accounting for 73.4% of the total installed capacity, which determines that more than 70% of my country's power fuel comes from coal. During the "Eleventh Five-Year Plan" period, in accordance with the unified requirements and deployment of the country, the power industry actively promoted the "increasing the large and reducing the small", optimized the power supply structure, and completed the energy-saving and emission-reduction planning goals ahead of schedule, making important contributions to the realization of the national energy-saving and emission-reduction goals. . At the same time, as the coal consumption of my country's coal-fired power units is close to the international advanced level, the space for energy conservation and emission reduction is gradually shrinking. Coal power enterprises must achieve energy conservation and emission reduction goals through innovations in production technology and methods.

The fuel distribution method of traditional coal power enterprises is: the raw coal is transported from the coal mine to the raw coal yard of the coal power enterprise, after being crushed by the coal crusher in the raw coal yard, it is sent to the raw coal bunker through the coal conveyor belt, and sent to the coal mill by the coal feeder. Grinding into fine coal powder, the coal powder enters the cyclone separator under the conveyance of hot air, and the separated fine coal powder falls into the coal powder bin, and the fine coal powder that comes down from the coal powder bin passes through the powder feeder and the hot air and fine coal powder are injected into the furnace through the burner for combustion.

There are many problems in this traditional production mode:

Coal freight accounts for a large part of the production cost of coal power enterprises. my country's coal resources are mainly concentrated in the northwestern region. Due to the local balanced development of electricity in my country for a long time in the past, coal power construction is more distributed to the east and central load centers, forming a large-scale, long-distance coal transportation. pattern. From the place of origin to the power plant, coal has to go through many links such as railway transportation, sea transportation, and road transportation, which further promotes the rise in the price of thermal coal. The proportion of thermal coal transportation costs in power generation costs is getting higher and higher. In 2003, East China and other places have reached above 50. It not only brings a heavy burden to the production and operation of coal power enterprises, but also brings prominent problems such as tight transportation capacity and repeated shutdowns due to lack of coal in power plants. According to statistics, 40% of the country's railway transportation and 30% of the total water transportation are mostly used for coal transportation, which is one of the factors causing tension in railway and water transportation. my country's coal transportation distance is long, the quantity of transportation is large, and it contains a certain amount of moisture, especially lignite, the moisture content of raw coal can reach about 30%, and "water transportation" accounts for a large part of transportation costs, resulting in waste of transportation capacity and increased production costs of coal power enterprises.

Raw coal is transported by box-type open car, which not only loses raw coal along the way, seriously pollutes the environment, but also poses a threat to the safe operation of trains. During coal transportation, due to the high-speed operation of the train or the pressure change during the meeting, the raw coal particles are splashed, and the dust pollution forms a pollution black belt along the railway line, and the growth of crops within 50-100m along the line is affected. Especially at the entrance of the train entering the tunnel, the dust and splash of coal particles are more serious. The coal layer scattered on the line can exceed the top of the track in a short time, and is continuously rolled by the train to form secondary dust. When the train passes through the tunnel, The dust concentration in the tunnel is likely to reach the explosion limit of pulverized coal, and it will cause an explosion accident when encountering an open flame, endangering driving safety. According to the statistics of the National Development and Reform Commission, in 2010, the national railway coal shipment was close to 2 billion tons. Calculated according to the country's 1.2% consumption rate of raw coal transported by railway box-type gondola car, the annual loss of raw coal is 24 million tons, which is equivalent to the annual coal production of a large coal mine.

Coal power enterprises need to design and build a huge pulverization system. The main equipment includes coal mills, coal feeders, coarse powder separators, fine powder separators, pulverizers, and pulverizer exhaust fans. In traditional pulverized coal boilers, it is an important part of the integral combustion system composed of boiler combustion equipment. At present, domestic power plants generally adopt a unit pulverization system in which each boiler unit is equipped with a separate pulverization system. There are many problems in the existing unit milling system.

The milling system is huge and takes up a lot of land resources. Coal power enterprises need to set up raw coal yards to store fuel coal, set up drying sheds in coal yards, and install facilities and crushing equipment for removing impurities in raw coal in the raw coal supply system.

The equipment margin of the unit milling system is relatively high, and there is a resource fee. Since the unit pulverization system is generally used at present, each boiler unit is equipped with a separate pulverization system, the coordination and control relationship between units is not close, the initial investment of the pulverization system is large, and large-scale production cannot be achieved. In order to ensure the continuous output of the boiler, the coal pulverizer of each boiler has a certain design margin. According to the requirements of DL/T5145-2002 "Technical Regulations for Design and Calculation of Coal Milling System in Thermal Power Plants", the coal pulverizer other than the spare coal pulverizer is designed The total output should not be less than 110% of the fuel consumption at the maximum continuous evaporation of the boiler. Except that the steel ball coal mill does not need backup, other types of coal mills need to have one spare for each boiler. But at present, many generating units in our country are involved in power grid peak regulation. According to the data from the National Generating Unit Technical Cooperation Association, the average load factor of 600MW generating units nationwide in 2010 was 73.86%, and the average load factor of 300MW generating units was 74.2%. It cannot run at full capacity, and there is a great waste of resources in the unit milling system.

The pulverizing system is closely related to the safety and economy of the unit. The pulverizing system of the coal-fired generating set is huge, the working conditions are harsh, and the failure rate is high, which is one of the main factors for the unplanned outage of the unit. The safe and economical operation of the pulverizing system directly affects the normal operation of the generating set. In the process of coal powder preparation and combustion in coal power enterprises, coal powder spontaneous combustion and explosion problems are often encountered for highly volatile coal types. It is easy to cause an explosion due to spontaneous combustion of coal powder. Although with the improvement and development of the boiler pulverization system, large-capacity boilers basically adopt the direct blowing pulverization system, which reduces the link where the pulverized coal is easy to spontaneously ignite due to the stacked state, but there is still a coal pulverization explosion in the pulverization system. Hidden dangers not only damage the equipment, but also seriously threaten the safety of the person and the unit, increasing the outage rate of the unit, labor costs and maintenance costs.

Pulverizing system is one of the important pollution sources of coal power enterprises. Generally, the pulverizing system has serious air leakage and dust pollution. At the same time, the noise pollution generated by the coal mill is very large. Moreover, once an accident such as an explosion occurs in the pulverizing system, serious environmental pollution will occur.

Under the dual pressure of increasing coal power production costs and energy conservation and emission reduction targets, coal power companies urgently need to change their production and operation models.

The centralized pulverization system refers to the establishment of a workshop or pulverization plant specially for the preparation of coal powder. The raw coal is first dried with a dryer, and then sent to a coal mill to be ground into qualified coal powder. Pulverized coal is transported to coal power enterprises for use by tank trucks or pneumatic conveying. The pulverized coal produced by the centralized pulverizing system is not only used by coal power enterprises, but also can be used to provide pulverized coal to users such as industrial pulverized coal boilers and iron and steel enterprises. It is a pulverized coal preparation technology worthy of development and application.

The use of centralized pulverizing systems in foreign power plants began in the 1930s. In 1927, the United States used 7 sets of 27 new power plants at that time to dry raw coal with steam or flue gas. Many sets of centralized milling systems have been put into use in Germany, most of which use steam tube dryers. The former Soviet Union also put into use some centralized milling systems in the 1930s and 1940s, most of which used steam tube dryers, and some used flue gas drums. The first centralized pulverizing system was installed in the Kasilsk Power Plant, built in 1930 and put into operation in 1932. Process features: After the raw coal is crushed and screened in two stages, it is input into the steam tube dryer, and the dried coal is input into the tipping bucket elevator, and mixed with fine coal into the rotary centrifugal separator. The supported pulverized coal is fed into the powder delivery pipe with a pneumatic screw pump, and is transported to the boiler powder bin by compressed air. The 800MW anthracite-burning boiler unit of the Slavyansk Power Plant in Russia uses a centralized pulverizing system, a large-scale steam tube dryer with a heating surface of ^4000m2 and a steel ball drum coal mill, and the pulverized coal is supplied by a pneumatic screw pump. The pulverized coal pipe is transported to the boiler powder bin by compressed air. Zolovsk Power Plant burns lignite 500MW boiler centralized pulverization system, the raw coal is input into the steam tube dryer for drying, the dry coal is input into the high-speed hammer mill, exhaust gas and part of the dry coal powder brought out by the dryer Lead out from the unloading chamber, the dust-laden air flow is purified by the multi-tubular cyclone separator and wet dust collector, and then discharged into the atmosphere, the coal powder is brought into the separator by the flue gas-air mixed air flow, and the captured coal powder enters the powder storage , and then sent to the boiler powder bin by pneumatic screw pump.

The centralized pulverization system in foreign countries is still limited to the interior of coal power enterprises. The transportation of raw coal is unavoidable. Coal power enterprises must also build raw coal yards and huge pulverization systems. Dust pollution and noise pollution in the enterprise cannot be avoided.

The domestic Coal Research Institute has conducted some research on the pulverization system, and published the patent "A Coal Powder Preparation System and Process". The coal powder preparation system is an independent coal powder preparation system, including a crushing system, a drying system and Grinding system, which mainly focuses on the preparation process of pulverized coal, is limited to pulverization in front of industrial pulverized coal furnaces, and does not consider the safety issues in the process of pulverized coal preparation and transportation, although the patent mentions the need to transport pulverized coal outside problem, but was not considered in detail. This system is an integrated system that utilizes the waste heat and flue gas of power plants in mining areas to make pulverized coal. It considers the safety issues of waste heat utilization, pulverized and transportation processes in detail. This invention is mainly used for coal power enterprises and Other pulverized coal users provide centralized pulverizing plants for pulverized coal.

Invention content:

Aiming at the current situation of electric power enterprises and the problems existing in domestic and foreign centralized pulverizing systems, the present invention provides a safe and efficient large-scale pulverized coal centralized preparation system and distribution method.

In order to achieve the above tasks, the present invention adopts the following technical solutions: a large-scale pulverized coal centralized preparation system, which mainly includes: boilers, steam turbines, generators, condensers, flue gas purification devices, condensing heat exchangers, crushed coal Machines, dryers, coal mills, air powder separators, bag filters, coal powder bins, inert gas storage containers, inerting protection devices, coal powder storage containers and coal powder handling equipment.

The coal crusher is connected to the coal mill through a dryer, and the coal mill is connected with an air-powder separator, and the air-powder separator is respectively connected with a coal powder bin and a bag filter; the boiler is connected with a flue gas purification device, and the flue gas A condensing heat exchanger is connected to the gas purification device; the pulverized coal bin is connected to a pulverized coal storage container, and an inerting protection device is installed inside the pulverized coal storage container, and the inerting protection device is connected to the inert gas storage container, and the pulverized coal storage container is connected to Pulverized coal loading and unloading equipment; the boiler is connected with a steam turbine, the steam turbine is connected with the generator, and the exhaust steam of the steam turbine enters the condenser.

The flue gas produced by the combustion of the boiler enters the flue gas purification device; the flue gas enters the condensing heat exchanger through the outlet of the flue gas purification device to condense and cool down to remove the water vapor in the flue gas;

The steam turbine is rotated by the main steam to drive the generator to generate electricity, and the exhaust steam of the steam turbine enters the condenser;

The raw coal is crushed into coal lumps in the coal crusher, and the coal lumps are sent to the dryer for drying;

The drying heat source dries the coal in the dryer, and the first exhaust steam discharged from the dryer enters the waste heat utilization device for waste heat utilization;

The dried coal is sent to the coal mill for grinding;

Qualified pulverized coal ground by the coal mill enters the air powder separator under the carrying of the gas, the separated coal powder enters the coal powder bin, and the second exhaust gas discharged from the air powder separator enters the bag filter;

The bag filter further purifies the second exhaust gas and then empties it, and the pulverized coal collected by the bag filter enters the pulverized coal bin;

The pulverized coal in the pulverized coal bin enters the pulverized coal storage container for storage;

An inert protection device is installed in the pulverized coal storage container to implement inert protection for the pulverized coal storage container;

The inert gas storage container stores the inert gas;

The pulverized coal preparation system mainly provides qualified pulverized coal for external transportation, and the system utilizes the waste heat of power generation enterprises; the distribution method adopted ensures the feasibility and safety of pulverized coal transportation, saves raw coal, reduces transportation volume, and eases traffic pressure, the quality of pulverized coal can be guaranteed; for coal power companies, the company does not need to build a huge pulverized coal preparation system, which reduces the floor area and power consumption rate of the plant, increases the power on the grid, and improves the safe and economical operation time of the unit; the entire distribution The process can be fully sealed, reducing the dust pollution of enterprises during transportation and storage; at the same time, it can effectively promote the promotion of high-efficiency industrial pulverized coal boilers, which has great economic and social benefits.

Description of drawings:

Fig. 1 is a kind of system working principle diagram embodying the present invention;

Fig. 2 is another kind of application example of the present invention;

Among them: 1 is a boiler; 2 is a flue gas purification device; 3 is a large steam turbine; 4 is a generator; 5 is a condenser; 6 is a coal crusher; 7 is a dryer; 8 is a condensing heat exchanger; 9 is The second heat exchanger; 10 is a coal mill; 11 is a bag filter; 12 is a wind powder separator; 13 is a coal powder bin; 14 is an inerting protection device; 15 is a coal storage container; 16 is an inert gas storage Container; 17 is a tank car; 18 is a pulverized coal handling equipment; 19 is a small steam turbine; 20 is an air separation unit.

Detailed ways:

The present invention is described in further detail below in conjunction with accompanying drawing:

As shown in Figure 1, the system mainly includes: boiler, large steam turbine, generator, small steam turbine, air separation unit, flue gas purification device, condenser, condensing heat exchanger, second heat exchanger, coal crusher , coal mill, dryer, wind powder separator, bag filter, coal powder bin, coal powder storage container, inert gas storage container, inert protection device, tanker, coal powder loading and unloading equipment. The boiler organizes oxygen-enriched combustion, and the required oxygen is generated by the air separation unit. The flue gas generated by the combustion passes through each heating surface in turn and then enters the flue gas purification device. The outlet of the flue gas purification device is divided into two parts, one part is sent to the furnace, and the other part is first The condensing heat exchanger condenses and cools down, and then passes through the second heat exchanger, where it is heated up and then enters the coal mill;

The large steam turbine is driven by the main steam to drive the generator to generate electricity, and the exhaust steam of the large steam turbine enters the condenser;

The air separation unit is driven by a small steam turbine, and the nitrogen produced by it is passed into the inert gas storage container for storage. The oxygen absorbs the sensible heat of the exhaust gas and the latent heat of the water vapor in the flue gas through the condensing heat exchanger, and reduces the temperature of the flue gas to the dew point temperature. Below, the heated oxygen is mixed with part of the flue gas in a certain proportion and then enters the boiler to organize oxygen-enriched combustion;

The small steam turbine is driven by steam extraction from the large steam turbine, and the exhaust steam from the small steam turbine enters the condenser;

The drying heat source of the dryer comes from the extraction steam of the steam turbine. The drying heat source dries the crushed raw coal in the dryer. The first exhaust steam discharged from the dryer enters the second heat exchanger, and heats the low-temperature steam that is cooled by the condensing heat exchanger. smoke;

The dried raw coal is sent to the coal mill for grinding, and the flue gas heated up from the second heat exchanger enters the coal mill as the conveying medium and protective gas;

Qualified pulverized coal ground by the coal mill enters the air powder separator under the carrying of the gas, the separated coal powder enters the coal powder bin, and the second exhaust gas discharged from the air powder separator enters the bag filter;

The bag filter further purifies the second exhaust gas and then empties it, and the pulverized coal collected by the bag filter enters the pulverized coal bin;

A small part of the pulverized coal in the pulverized coal bin is sent to the boiler for combustion, and most of it is stored in the pulverized coal storage container. The pulverized coal storage container is equipped with an inert protection device to ensure that the entire storage bin is in an inert atmosphere;

The pulverized coal in the pulverized coal storage container is unloaded into the tank car through the pulverized coal loading and unloading equipment, and then filled with nitrogen to implement inert protection to ensure that the tank car is under a slight positive pressure condition to prevent air leakage.

The working process of the system is that the boiler organizes oxygen-enriched combustion, and the steam generated drives a large steam turbine, which drives a generator to generate electricity. The large steam turbine is used to extract steam to drive the small steam turbine, and then the air separation unit is driven to generate oxygen and nitrogen. The oxygen is passed into the furnace to organize oxygen-enriched combustion, and the nitrogen enters the inert gas storage container. The steam extracted from the large steam turbine is used as a drying heat source and enters the dryer to dry the raw coal. The first exhaust steam discharged from the dryer enters the second heat exchanger for waste heat utilization, and the dried raw coal enters the coal mill. Part of the purified flue gas enters the condensing heat exchanger to cool down to below the acid dew point temperature to remove the remaining acid gas and water vapor in the flue gas, and then enters the second heat exchanger for heating. The flue gas is carried into the air powder separator, and the pulverized coal separated by the air powder separator enters the pulverized coal bin. The second exhaust gas is emptied after dust removal by the bag filter, and the pulverized coal collected by the bag filter enters the pulverized coal bin. . A small part of the pulverized coal in the pulverized coal bin enters the boiler for combustion, and most of it enters the pulverized coal storage container for storage. Nitrogen is charged from the inert gas storage container into the pulverized coal storage container through the inert protection device, so that the pulverized coal is in an inert atmosphere to ensure that it will not explode. After the pulverized coal transport tanker is filled with pulverized coal, it is also filled with nitrogen to ensure the safety of pulverized coal transportation.

Referring to Fig. 2, Fig. 2 is another application example of the present invention. The difference from Example 1 is that the inert gas uses purified flue gas, and the flue gas generated by the boiler combustion passes through the flue gas purification device and the condensing heat exchanger, and then part of it enters the inert gas storage container for storage, and part of it passes through the second heat exchanger After heating up, it enters the coal mill to transport the qualified pulverized coal. The flue gas stored in the inert gas storage container is inerted and protected by the inert protection device for the pulverized coal storage container and pulverized coal conveying equipment.

The above content is a further detailed description of the present invention in conjunction with specific preferred embodiments. It cannot be determined that the specific embodiments of the present invention are limited thereto. Under the circumstances, some simple deduction or replacement can also be made, all of which should be regarded as belonging to the scope of patent protection determined by the submitted claims of the present invention.

Claims (9)

1. a large-scale concentrative coal powder preparation system, it is characterized in that, this system mainly comprises: boiler, large steam turbine, generator, condenser, smoke eliminator, condensing heat exchanger, coal breaker, drier, coal pulverizer, wind powder separator, sack cleaner, Pulverized Coal Bin, the inert gas reservoir vessel, inertia protection device, coal dust reservoir vessel and coal dust handling facilities, the drying source of drier carrys out drawing gas of arrogant steam turbine, described coal breaker connects coal pulverizer by drier, be connected with wind powder separator on coal pulverizer, connect respectively Pulverized Coal Bin and sack cleaner on wind powder separator, be connected with smoke eliminator on described boiler, be connected with condensing heat exchanger on smoke eliminator, described Pulverized Coal Bin connects the coal dust reservoir vessel, and coal dust reservoir vessel inside arranges inertia protection device, and inertia protection device is connected with the inert gas reservoir vessel, and the coal dust reservoir vessel connects the coal dust handling facilities, described boiler is connected with large steam turbine, and large steam turbine is connected with generator, and large turbine discharge enters condenser,

Thereby be equipped with in described inert gas reservoir vessel, make coal dust avoid the protection gas of blasting under inert atmosphere, protection gas is flue gas or nitrogen through purifying; When adopting flue gas through purifying as protection gas, the outlet of condensing heat exchanger is divided into two-way, and a road is connected with the entrance of inert gas reservoir vessel, and another road is connected with coal pulverizer after the second heat exchanger heat exchange; When adopting nitrogen as protection gas; the outlet of condensing heat exchanger is connected with coal pulverizer after the second heat exchanger heat exchange; set up air separation unit and carbon dioxide capture device simultaneously; the nitrogen that air separation unit produces passes into the storage of inert gas reservoir vessel; the oxygen that air separation unit produces passes into boiler inner tissue oxygen-enriched combusting, afterbody carbon dioxide capture device capturing carbon dioxide.

2. large-scale concentrative coal powder preparation system as claimed in claim 1 is characterized in that:

The flue gas that boiler combustion produces enters smoke eliminator; Flue gas enters the condensing heat exchanger condensation through the smoke eliminator outlet and lowers the temperature to remove the steam in flue gas;

Large steam turbine promotes rotation by main steam, drives the generator generating, and large turbine discharge enters condenser;

Raw coal is broken for coal cinder in coal breaker, and coal cinder is sent into drier and carried out drying;

Drying source carries out drying to coal cinder in drier, and the first exhaust steam that drier is discharged enters residual heat using device and carries out UTILIZATION OF VESIDUAL HEAT IN;

Dried coal cinder is sent into coal pulverizer and is ground;

The qualified coal dust ground by coal pulverizer enters wind powder separator under the carrying of gas, and the coal dust after separation enters Pulverized Coal Bin, and the second weary gas of being discharged by wind powder separator enters sack cleaner;

Sack cleaner is emptying after further the second weary gas being purified, and the coal dust that sack cleaner is collected enters Pulverized Coal Bin;

The coal dust of Pulverized Coal Bin enters the coal dust reservoir vessel and deposits.

3. the system as claimed in claim 1, is characterized in that: described boiler employing raw coal, gangue, coal bed gas fuel single fire or multifuel combustion.

4. the system as claimed in claim 1 is characterized in that: hot-air, steam or flue gas that described drier adopts coal electricity enterprise to produce are as drying source.

5. the system as claimed in claim 1 is characterized in that: described coal pulverizer type of drive comprises and adopts driven by power and small steam turbine to drive.

6. the system as claimed in claim 1, it is characterized in that: described smoke eliminator is in order to remove most sour gas, flyash and heavy metal vapor in flue gas.

7. the system as claimed in claim 1, it is characterized in that: the dividing wall type heat exchanger that described condensing heat exchanger adopts resistant material to make, flue gas discharges the latent heat of steam in smoke evacuation sensible heat and flue gas in condensing heat exchanger, and temperature is reduced to below dew-point temperature.

8. the system as claimed in claim 1, is characterized in that: inertia protection device is installed in described coal dust reservoir vessel the coal dust reservoir vessel is implemented to inactive protect.

9. the allocator of a coal dust of producing based on the described system of claim 1; it is characterized in that: the method comprises and adopts railway, highway or water route to seal canned conveying or pipeline pulverized coal conveying to the coal dust user, and tank is filled with inert gas enforcement inactive protect after filling it up with coal dust.